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diff --git a/components/shared/script_layout/message.rs b/components/shared/script_layout/message.rs
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+++ b/components/shared/script_layout/message.rs
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+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/. */
+
+use std::sync::atomic::AtomicBool;
+use std::sync::Arc;
+
+use app_units::Au;
+use crossbeam_channel::{Receiver, Sender};
+use euclid::default::{Point2D, Rect};
+use gfx_traits::Epoch;
+use ipc_channel::ipc::{IpcReceiver, IpcSender};
+use malloc_size_of_derive::MallocSizeOf;
+use metrics::PaintTimeMetrics;
+use msg::constellation_msg::{BackgroundHangMonitorRegister, BrowsingContextId, PipelineId};
+use net_traits::image_cache::ImageCache;
+use profile_traits::mem::ReportsChan;
+use script_traits::{
+    ConstellationControlMsg, LayoutControlMsg, LayoutMsg as ConstellationMsg, Painter, ScrollState,
+    WindowSizeData,
+};
+use servo_arc::Arc as ServoArc;
+use servo_atoms::Atom;
+use servo_url::{ImmutableOrigin, ServoUrl};
+use style::animation::DocumentAnimationSet;
+use style::context::QuirksMode;
+use style::dom::OpaqueNode;
+use style::invalidation::element::restyle_hints::RestyleHint;
+use style::properties::PropertyId;
+use style::selector_parser::{PseudoElement, RestyleDamage, Snapshot};
+use style::stylesheets::Stylesheet;
+
+use crate::rpc::LayoutRPC;
+use crate::{PendingImage, TrustedNodeAddress};
+
+/// Asynchronous messages that script can send to layout.
+pub enum Msg {
+    /// Adds the given stylesheet to the document. The second stylesheet is the
+    /// insertion point (if it exists, the sheet needs to be inserted before
+    /// it).
+    AddStylesheet(ServoArc<Stylesheet>, Option<ServoArc<Stylesheet>>),
+
+    /// Removes a stylesheet from the document.
+    RemoveStylesheet(ServoArc<Stylesheet>),
+
+    /// Change the quirks mode.
+    SetQuirksMode(QuirksMode),
+
+    /// Requests a reflow.
+    Reflow(ScriptReflow),
+
+    /// Get an RPC interface.
+    GetRPC(Sender<Box<dyn LayoutRPC + Send>>),
+
+    /// Requests that the layout thread measure its memory usage. The resulting reports are sent back
+    /// via the supplied channel.
+    CollectReports(ReportsChan),
+
+    /// Requests that the layout thread enter a quiescent state in which no more messages are
+    /// accepted except `ExitMsg`. A response message will be sent on the supplied channel when
+    /// this happens.
+    PrepareToExit(Sender<()>),
+
+    /// Requests that the layout thread immediately shut down. There must be no more nodes left after
+    /// this, or layout will crash.
+    ExitNow,
+
+    /// Get the last epoch counter for this layout thread.
+    GetCurrentEpoch(IpcSender<Epoch>),
+
+    /// Asks the layout thread whether any Web fonts have yet to load (if true, loads are pending;
+    /// false otherwise).
+    GetWebFontLoadState(IpcSender<bool>),
+
+    /// Creates a new layout thread.
+    ///
+    /// This basically exists to keep the script-layout dependency one-way.
+    CreateLayoutThread(LayoutThreadInit),
+
+    /// Set the final Url.
+    SetFinalUrl(ServoUrl),
+
+    /// Tells layout about the new scrolling offsets of each scrollable stacking context.
+    SetScrollStates(Vec<ScrollState>),
+
+    /// Tells layout that script has added some paint worklet modules.
+    RegisterPaint(Atom, Vec<Atom>, Box<dyn Painter>),
+
+    /// Send to layout the precise time when the navigation started.
+    SetNavigationStart(u64),
+}
+
+#[derive(Debug, PartialEq)]
+pub enum NodesFromPointQueryType {
+    All,
+    Topmost,
+}
+
+#[derive(Debug, PartialEq)]
+pub enum QueryMsg {
+    ContentBoxQuery(OpaqueNode),
+    ContentBoxesQuery(OpaqueNode),
+    ClientRectQuery(OpaqueNode),
+    ScrollingAreaQuery(Option<OpaqueNode>),
+    OffsetParentQuery(OpaqueNode),
+    TextIndexQuery(OpaqueNode, Point2D<f32>),
+    NodesFromPointQuery(Point2D<f32>, NodesFromPointQueryType),
+
+    // FIXME(nox): The following queries use the TrustedNodeAddress to
+    // access actual DOM nodes, but those values can be constructed from
+    // garbage values such as `0xdeadbeef as *const _`, this is unsound.
+    NodeScrollIdQuery(TrustedNodeAddress),
+    ResolvedStyleQuery(TrustedNodeAddress, Option<PseudoElement>, PropertyId),
+    StyleQuery,
+    ElementInnerTextQuery(TrustedNodeAddress),
+    ResolvedFontStyleQuery(TrustedNodeAddress, PropertyId, String),
+    InnerWindowDimensionsQuery(BrowsingContextId),
+}
+
+/// Any query to perform with this reflow.
+#[derive(Debug, PartialEq)]
+pub enum ReflowGoal {
+    Full,
+    TickAnimations,
+    LayoutQuery(QueryMsg, u64),
+
+    /// Tells layout about a single new scrolling offset from the script. The rest will
+    /// remain untouched and layout won't forward this back to script.
+    UpdateScrollNode(ScrollState),
+}
+
+impl ReflowGoal {
+    /// Returns true if the given ReflowQuery needs a full, up-to-date display list to
+    /// be present or false if it only needs stacking-relative positions.
+    pub fn needs_display_list(&self) -> bool {
+        match *self {
+            ReflowGoal::Full | ReflowGoal::TickAnimations | ReflowGoal::UpdateScrollNode(_) => true,
+            ReflowGoal::LayoutQuery(ref querymsg, _) => match *querymsg {
+                QueryMsg::NodesFromPointQuery(..) |
+                QueryMsg::TextIndexQuery(..) |
+                QueryMsg::InnerWindowDimensionsQuery(_) |
+                QueryMsg::ElementInnerTextQuery(_) => true,
+                QueryMsg::ContentBoxQuery(_) |
+                QueryMsg::ContentBoxesQuery(_) |
+                QueryMsg::ClientRectQuery(_) |
+                QueryMsg::ScrollingAreaQuery(_) |
+                QueryMsg::NodeScrollIdQuery(_) |
+                QueryMsg::ResolvedStyleQuery(..) |
+                QueryMsg::ResolvedFontStyleQuery(..) |
+                QueryMsg::OffsetParentQuery(_) |
+                QueryMsg::StyleQuery => false,
+            },
+        }
+    }
+
+    /// Returns true if the given ReflowQuery needs its display list send to WebRender or
+    /// false if a layout_thread display list is sufficient.
+    pub fn needs_display(&self) -> bool {
+        match *self {
+            ReflowGoal::Full | ReflowGoal::TickAnimations | ReflowGoal::UpdateScrollNode(_) => true,
+            ReflowGoal::LayoutQuery(ref querymsg, _) => match *querymsg {
+                QueryMsg::NodesFromPointQuery(..) |
+                QueryMsg::TextIndexQuery(..) |
+                QueryMsg::ElementInnerTextQuery(_) => true,
+                QueryMsg::ContentBoxQuery(_) |
+                QueryMsg::ContentBoxesQuery(_) |
+                QueryMsg::ClientRectQuery(_) |
+                QueryMsg::ScrollingAreaQuery(_) |
+                QueryMsg::NodeScrollIdQuery(_) |
+                QueryMsg::ResolvedStyleQuery(..) |
+                QueryMsg::ResolvedFontStyleQuery(..) |
+                QueryMsg::OffsetParentQuery(_) |
+                QueryMsg::InnerWindowDimensionsQuery(_) |
+                QueryMsg::StyleQuery => false,
+            },
+        }
+    }
+}
+
+/// Information needed for a reflow.
+pub struct Reflow {
+    ///  A clipping rectangle for the page, an enlarged rectangle containing the viewport.
+    pub page_clip_rect: Rect<Au>,
+}
+
+/// Information derived from a layout pass that needs to be returned to the script thread.
+#[derive(Default)]
+pub struct ReflowComplete {
+    /// The list of images that were encountered that are in progress.
+    pub pending_images: Vec<PendingImage>,
+}
+
+/// Information needed for a script-initiated reflow.
+pub struct ScriptReflow {
+    /// General reflow data.
+    pub reflow_info: Reflow,
+    /// The document node.
+    pub document: TrustedNodeAddress,
+    /// The dirty root from which to restyle.
+    pub dirty_root: Option<TrustedNodeAddress>,
+    /// Whether the document's stylesheets have changed since the last script reflow.
+    pub stylesheets_changed: bool,
+    /// The current window size.
+    pub window_size: WindowSizeData,
+    /// The channel that we send a notification to.
+    pub script_join_chan: Sender<ReflowComplete>,
+    /// The goal of this reflow.
+    pub reflow_goal: ReflowGoal,
+    /// The number of objects in the dom #10110
+    pub dom_count: u32,
+    /// The current window origin
+    pub origin: ImmutableOrigin,
+    /// Restyle snapshot map.
+    pub pending_restyles: Vec<(TrustedNodeAddress, PendingRestyle)>,
+    /// The current animation timeline value.
+    pub animation_timeline_value: f64,
+    /// The set of animations for this document.
+    pub animations: DocumentAnimationSet,
+}
+
+pub struct LayoutThreadInit {
+    pub id: PipelineId,
+    pub url: ServoUrl,
+    pub is_parent: bool,
+    pub layout_pair: (Sender<Msg>, Receiver<Msg>),
+    pub pipeline_port: IpcReceiver<LayoutControlMsg>,
+    pub background_hang_monitor_register: Box<dyn BackgroundHangMonitorRegister>,
+    pub constellation_chan: IpcSender<ConstellationMsg>,
+    pub script_chan: IpcSender<ConstellationControlMsg>,
+    pub image_cache: Arc<dyn ImageCache>,
+    pub paint_time_metrics: PaintTimeMetrics,
+    pub layout_is_busy: Arc<AtomicBool>,
+    pub window_size: WindowSizeData,
+}
+
+/// A pending restyle.
+#[derive(Debug, MallocSizeOf)]
+pub struct PendingRestyle {
+    /// If this element had a state or attribute change since the last restyle, track
+    /// the original condition of the element.
+    pub snapshot: Option<Snapshot>,
+
+    /// Any explicit restyles hints that have been accumulated for this element.
+    pub hint: RestyleHint,
+
+    /// Any explicit restyles damage that have been accumulated for this element.
+    pub damage: RestyleDamage,
+}
+
+impl PendingRestyle {
+    /// Creates a new empty pending restyle.
+    #[inline]
+    pub fn new() -> Self {
+        PendingRestyle {
+            snapshot: None,
+            hint: RestyleHint::empty(),
+            damage: RestyleDamage::empty(),
+        }
+    }
+}